The present application relates generally to wind turbines and more particularly relates to wind turbine rotor blades and its accessory systems like flaps, winglets and spoilers, with mechanical elements for pretensioning a tension fabric skin structure.
Most environment friendly energy sources presently available come from wind power that is considered to be one of the cleanest. In this regard, wind turbines have gained increased attention. Wind turbines generate electricity by effectively harnessing energy in the wind via a rotor having a set of rotor blades that turns a gearbox and generator, thereby converting mechanical energy to electrical energy that may be deployed to a utility grid. The construction of a modern wind turbine rotor blade generally includes skin or shell components, span-wise extending spar caps, and one or more shear webs. Present technology uses several molds to fabricate the various pieces of composite wind blade that are bonded together in large resin-infused molds. Such finished blades are relatively heavy and includes a hardened shell encasing the molded hardened shear webs or spar caps. This leads to difficulty in transportation and assembly of the wind blades. Further, the size, shape, and weight of wind blades are factors that contribute to energy efficiencies of wind turbine. In order to reduce the weight of the composite wind blades, a tension fabric skin is being actively considered. One important aspect in the effectiveness of the tension fabric is the pretension in the fabric. This has to be maintained ideally at all operating conditions to obtain both aerodynamic and structural performance. However the fabric is known to loose tension and sag due to creep and other factors. This leads to degraded performance.
There is therefore a desire for a wind blade and method for improved aerodynamic and structural performance of the wind blade. Such wind blades should improve overall system efficiency while being inexpensive to fabricate and providing a long lifetime.